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Biomedical subjects

G Sanchez

Publications and source records attributed to G Sanchez.

At least 37 records · Page 2Linked to original sources
PubMed1995

Omeprazole in the long-term treatment of gastro-oesophageal reflux disease. A double-blind randomized dose-finding study.

BACKGROUND: Omeprazole is effective in the treatment of reflux oesophagitis, and it is important to determine the lower dose limit with still appropriate clinical efficacy. METHODS: Patients with endoscopic oesophagitis grade 1-4 (N = 220) were randomized to double-blind treatment with 20 mg or 40 mg omeprazole daily for 4-8 weeks. Those healed after this initial treatment phase were re-randomized to double-blind treatment with 20 mg omeprazole daily (n = 67), 10 mg omeprazole daily (n = 68), or placebo (n = 33) for 6 months. Remission was defined as the absence of any endoscopic sign of oesophagitis. RESULTS: Healing rates were increased with 40 mg omeprazole, the therapeutic gain compared with the 20-mg dose being 15% after 4 and 8 weeks. The proportion of patients in remission after 6 months was 59% with 20 mg omeprazole, 35% with 10 mg omeprazole, and 0% with placebo. CONCLUSION: Maintenance treatment with 10 mg omeprazole can prevent recurrence of oesophagitis in about one-third of patients with all grades of oesophagitis, and 20 mg omeprazole in about twice as many.

Adult↗
PubMed1994

Transcription by T7 RNA polymerase of DNA containing abasic sites.

The effects of abasic (AP) sites on RNA synthesis were studied in vitro, using T7 RNA polymerase and a plasmid template containing a T7 promoter. The presence of increasing numbers of AP sites caused a progressive decline in RNA synthesis. The average RNA chain length, calculated from the ratio of initiation to chain elongation, decreased with increasing numbers of AP sites, revealing that complete blocks must occur during synthesis. The probability that RNA polymerase would be blocked at an AP site in the DNA template strand was estimated to be 0.3 in our experimental conditions. These results demonstrate that RNA synthesis by T7 RNA polymerase is inhibited by AP sites and that readthrough of the lesion occurs more frequently than premature chain termination. Chemical reduction of AP sites in the template did not change the block/bypass pattern.

Apurinic Acid↗
PubMed1994

Effect of abasic sites on bacteriophage T7 protein synthesis.

We have examined protein synthesis directed by bacteriophage T7 which had been alkylated with methyl methanesulfonate so as to produce apurinic sites in its DNA in vivo. Both repair-proficient and repair-deficient (xth nfo mutant) strains of Escherichia coli served as host cells. In repair-proficient cells, all three classes of phage proteins were synthesized, although with significant delays. In mutant cells, only class I proteins were produced and their synthesis was delayed and reduced, demonstrating a perturbation of protein synthesis and providing the first in vivo indication that transcription is inhibited by abasic sites. However, the proposed effects of abasic sites on transcription appear to be weaker than those on replication.

Alkylation↗
PubMed1994

How parents cope with the experience of neonatal intensive care.

Thirty-two mothers and 25 fathers described their coping efforts during the initial weeks of their preterm infants' hospitalization in a neonatal intensive care unit. Utilizing procedures developed by Lazarus and Folkman (1984) in which coping is linked with a specific stressful event, parents reported what they did to cope with the stressor they perceived to be the most stressful. They also completed the Ways of Coping Questionnaire (Folkman & Lazarus, 1988). Results showed that there were similarities and differences in the types of coping strategies used by mothers and fathers. In addition, factors such as neonatal morbidity and appraisal of control were differentially associated with the use of certain types of coping strategies. Implications for future research and clinical practice are discussed.

Adaptation, Psychological↗
PubMed1994

Human nasal mucosal changes after exposure to urban pollution.

Millions of people worldwide are living in areas where ozone (O3) concentrations exceed health standards (an hourly average of 235 micrograms/m3/0.12 ppm, not to be exceeded more than once per year). Ozone induces acute nasal inflammatory responses and significant epithelial lesions in experimental animals and humans. To determine the nasal effects of a 15-day exposure to an urban polluted atmosphere with O3 as the main pollutant, we studied a population of healthy, young males newly arrived to southwest metropolitan Mexico City (SWMMC). The study included 49 non-smoking residents in an unpolluted port, Veracruz City; 14 subjects stayed in the port and served as controls, while 35 subjects traveled to SWMMC and had serial nasal lavages at different times after arriving in SWMMC. Subjects had exposures to ambient O3 an average of 10.2 hr/day, with a total cumulative O3 exposure of 10.644 ppm.hr. Nasal inflammatory responses, polymorphonuclear leukocyte PMN-CD11b surface expression, rhinoscopic changes, and respiratory symptoms were evaluated. Exposed subjects had massive nasal epithelial shedding and significant responses in PMN nasal influx (p < 0.00001) and in PMN-CD11b expression (p < 0.05). Cumulative O3 exposure correlated with respiratory symptoms, PMNs (rs = 0.2374, p < 0.01), and CD11b (rs = 0.3094, p < 0.01); 94% of exposed subjects experienced respiratory symptoms, and 97% left the city with an abnormal nasal mucosa by rhinoscopy. Nasal epithelial changes persisted 2 weeks after the exposed subjects returned to their nonpolluted environment. Exposure to an urban polluted atmosphere induces significant and persistent nasal epithelial alterations in healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Angiographic diagnosis and management of gastrointestinal hemorrhage. Current concepts.

Gastrointestinal bleeding is now seen less often by the angiographer than in the past, owing to advances in pharmacology, endoscopy, and nuclear medicine. When patients with gastrointestinal bleeding are referred, it is often for therapy as well as diagnosis. Therapeutic options include infusion of vasoconstrictors and selective embolization, which is usually faster and more definitive. Depending on the agent used, embolization is generally quite safe and effective. The risk of ischemia is significant only in the colon or when collateral pathways have been previously interrupted. The management of variceal bleeding has changed significantly due to the advent of TIPS and the increasing availability of liver transplantation.

Angiography↗
PubMed1993

Expression of unusual immunophenotype combinations in acute myelogenous leukemia.

Immunophenotypes for 272 patients with acute myelogenous leukemia (AML) were analyzed using a panel of 22 antibodies. Numerical evidence for unusual coexpressions (present in normal marrow at < or = 0.1%) of surface markers on > or = 10% of the blast cells was found in 85% of all cases. Asynchronous expression of myeloid differentiation antigens occurred in 70% of the cases. Unusual coexpression of T-lymphoid, B-lymphoid, or natural killer (NK) markers with myeloid markers occurred in 38%, 13%, and 21%, respectively, of all AML cases. Two- and three-color analyses confirmed coexpression in 15 of 15 cases, and indicated that these percentages are an underestimate, because coexpression can be demonstrated in cases without numerical overlap. These data indicate that the unusual coexpression of normal differentiation antigens is a common occurrence in AML. Markers in 12 of 13 patients were similar between presentation and relapse, and in two patients, unusual phenotypes detected at first relapse were shown at second relapse, indicating these immunophenotypes are stable in the majority of AML patients. Significant correlations were found between t(8;21) cytogenetics and coexpression of CD19 with CD15 or CD34, t(9;22) and coexpression of CD19 and CD34, and t(15;17) and coexpression of CD2 and myeloid antigens. Multiparameter fluorescence analysis allows detection of unusual phenotypes when the blast counts are < 5% (classical remission). Analysis of 16 patients in remission indicated the presence of presentation phenotypes in 0.2% to 7.9% of the lymphocyte + blast light scatter region, representing 0.03% to 1.4% of the total nucleated marrow cells. Of the 16 patients with > or = 4 months follow-up after detection of these cells, 6 of 6 patients with > or = 0.2% unusual presentation phenotypic marrow cells have relapsed, while 9 of 10 patients with < 0.2% remain in remission. The detection of cells with the unusual presentation phenotype may reflect residual AML cells, and their increase may predict relapse.

Adult↗
PubMed1993

The use of perfluorocarbon liquids in the repositioning of posteriorly dislocated intraocular lenses.

PURPOSE: Removal of intraocular lenses (IOLs) dislocated into the vitreous cavity can be hazardous and result in severe complications and visual loss. Recognizing limitations in current management, the authors developed a new, safer surgical technique to reduce intraoperative and postoperative complications. METHODS: The authors report eight eyes of eight patients with posteriorly dislocated IOLs in which perfluorocarbon liquids were injected into the eye after vitrectomy to float the IOL off the retina. The IOL haptics were repositioned in the residual capsular bag or ciliary sulcus, and the positioning holes of the optic were sutured to the sclerotomies under a scleral flap. RESULTS: With a minimum follow-up of 8 months (average, 12 months), all eight eyes improved in Snellen visual acuity, and six of them achieved a final Snellen visual acuity of 20/40 or better. Complications did not occur in any of the eight eyes. Preoperative cystoid macular edema resolved in three of four eyes, and the retina has remained attached in the one eye with a preoperative retinal detachment. CONCLUSION: Application of vitreoretinal microsurgical techniques and the use of liquid perfluorocarbons allow for the safer management of eyes with posteriorly dislocated IOLs.

Aged↗
PubMed1993

Characterization of Trypanosoma cruzi populations by several molecular markers supports a clonal mode of reproduction.

Chilean T. cruzi populations from different endemic areas and transmission cycles were characterized at several biochemical levels, to mention: hybridization with kinetoplast DNA probes, molecular karyotype, isoenzyme studies and kinetoplast DNA restriction fragment length polymorphism. Furthermore, an immunological approach with immune sera from Balb/c infected mice with different T. cruzi populations was used to differentiate among parasite types by the in vitro complement-mediated lysis assay. Parasite grouping by the above described methods allows to classify T. cruzi populations on a very defined number, suggesting that they have a clonal structure.

Animals↗
PubMed1992

A rare case of a multicentric peripheral ameloblastoma of the gingiva. A light and electron microscopic study.

A rare case of a multicentric peripheral ameloblastoma of the gingiva in a 54-year-old male patient is described along with a light and electron microscopic study of the excised tumors. The peripheral ameloblastoma is considered to be the gingival counterpart of the more common intraosseous ameloblastoma. Although both tumors have similar histomorphologic characteristics, their clinical appearance and behavior are completely different. The peripheral ameloblastoma is slow growing and non-invasive, and recurrence is uncommon following excision. The more common central ameloblastoma, is locally invasive and can destroy large segments of the jaw. The histogenesis of the peripheral ameloblastoma and several other odontogenic tumors of the gingiva serves to illustrate the proliferative potential of the basal cell layer of gingival epithelium.

Ameloblastoma↗
PubMed1992

Reactivity patterns and infection status of serum samples with indeterminate Western immunoblot tests for antibody to human immunodeficiency virus type 1.

Serum samples with indeterminate Western blot (WB) tests from 61 individuals whose sera were positive by enzyme-linked immunosorbent assay (ELISA) were studied in order to characterize their putative reactions with the human immunodeficiency virus (HIV) proteins and to resolve the HIV infection status of these individuals. The reaction observed by WB could not be confirmed either by radioimmunoprecipitation assay and subsequent electrophoresis (RIPA) or by use of LiaTek (Organon Teknika, Turnbout, The Netherlands) in 28% of the samples. Of the 86 samples that were indeterminate by WB, 66 reacted with p24 by WB; this reaction was confirmed by RIPA in only 21 (32%) and by LiaTek in 49 (74%) of the 66 samples. On the other hand, none of the indeterminate samples that reacted with HIV envelope proteins by WB did so by LiaTek, while 50% precipitated at least some of these proteins in the RIPA. The sensitivities of the three methods for detecting the antibody reaction with the different HIV proteins, which were studied with serial dilutions of positive serum samples, were similar. Thus, a lower sensitivity of RIPA or LiaTek does not seem to be the cause for the lack of reaction of the WB-indeterminate samples by these two methods. Sequential samples from individuals whose serum samples reacted by the three methods gave reproducible results, but all showed low antibody titers. Peripheral blood mononuclear cells obtained from three of the four individuals with sequential samples that reacted with HIV env proteins by WB and RIPA were negative for HIV provirus DNA after amplification by the polymerase chain reaction.

Blotting, Western↗
PubMed1992

Development of T7 phage and T7 phage containing apurinic sites in an exonuclease III, endonuclease IV double mutant of Escherichia coli.

The development of bacteriophage T7 was examined in an Escherichia coli double mutant defective for the two major apurinic, apyrimidinic endonucleases (exonuclease III and endonuclease IV, xth nfo). In cells infected with phages containing apurinic sites, the defect in repair enzymes led to a decrease of phage survival and a total absence of bacterial DNA degradation and of phage DNA synthesis. These results directly demonstrate the toxic action of apurinic sites on bacteriophage T7 at the intracellular level and its alleviation by DNA repair. In addition, untreated T7 phage unexpectedly displayed reduced plating efficiency and decreased DNA synthesis in the xth nfo double mutant.

Bacterial Proteins↗
PubMed1992

Impaired atrial natriuretic factor systemic clearance contributes to its higher levels in uremia.

To evaluate the interaction between plasma levels and the systemic uptake of atrial natriuretic factor (ANF) with thyroid hormone levels during acute renal failure (ARF), seven groups of rats were analyzed: Group 1, Controls (C); Group 2, ARF; Group 3, filtering kidney with uremia; Group 4, ARF with thyroxine (T4) supplement (ARF + T4); Group 5, thyroidectomy (Tx); Group 6, ARF on Tx rats (Tx + ARF); Group 7, Tx + ARF supplemented with T4 (Tx + ARF + T4). Plasma creatinine (Cr), urea, T4, blood volume, and ANF were measured; ANF half-life (ANF t1/2; expressed in seconds) was calculated. Rats with ARF developed uremia (Cr, 377 +/- 58 versus 41 +/- 5 mumol/L), significant reduction in T4 (40 +/- 4 versus 89.2 +/- 6 nmol/L). elevation of ANF (287.7 +/- 35 versus 60.9 +/- 8 fmol/mL), and lengthening of ANF t1/2 (69.7 +/- 8 versus 37.2 +/- 6 s) compared with C (P less than 0.01). T4 supplements to ARF rats resulted in a lesser degree of uremia (Cr, 283 +/- 27; P less than 0.05) and normalization of ANF t1/2 (31.4 +/- 5); however, ANF levels remained higher than C (100.4 +/- 11.4 versus 60.9 +/- 8; P less than 0.01). Tx by itself did not change either parameter. The filtering kidney with uremia group developed mild uremia (Cr, 199 +/- 8), T4 fell (58 +/- 8), ANF levels rose (83.4 +/- 5.4), and ANF t1/2 was prolonged (54.5 +/- 12). Tx before ARF doubled the ANF level and lengthened ANF t1/2 similarly than in ARF. T4 addition (Tx + ARF + T4) normalized ANF t1/2 (29.8 +/- 3) in spite of a persistently high ANF (145.7 +/- 21). Blood volume did not change in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Polymorphism of the alleles of the merozoite surface antigens MSA1 and MSA2 in Plasmodium falciparum wild isolates from Colombia.

The degree of polymorphism and the allelic distribution of 2 major Plasmodium falciparum merozoite surface antigens (MSA1 and MSA2) have been analysed in clinical isolates from Colombia. DNA was prepared directly from patients' blood and used in PCR reactions to amplify block 2 of MSA1 and the central region from MSA2. Thirty one samples were analysed and a marked degree of length polymorphism was detected, especially for MSA2. A high proportion of multiple bands was also observed, most probably resulting from mixed infections. Allele-specific oligonucleotides were used to type both alleles. For MSA1, 26 out of 31 clinical isolates were of the RO33 type, 15 were MAD20 and three were typed as KI. When the MSA2 allele was analysed, 7 isolates hybridised with a CAMP specific probe and 6 hybridised strongly with an FC27-derived oligonucleotide. Two samples, which showed multiple bands, hybridised with both probes. Interestingly, in 14 out of 27 isolates the MSA2 allele remained unassigned by the specific probes. Five of these were cloned and their DNA sequenced; these sequences are discussed.

Adolescent↗
PubMed1990

Biological characterization of Trypanosoma cruzi zymodemes: in vitro differentiation of epimastigotes and infectivity of culture metacyclic trypomastigotes to mice.

Thirty-one Trypanosoma cruzi isolates from Chile, Peru, and Bolivia were studied in their capacity to differentiate in vitro from epimastigotes to metacyclic trypomastigotes on TAU-3AAG medium. Zymodeme 1 parasites displayed the best level of differentiation, which ranges from 60 to 90% depending on the isolate. Zymodeme 2 parasites exhibited highly heterogenous differentiation rates. This differentiation method permits the obtention of large amounts of metacyclic trypomastigotes from zymodeme 1 parasites. Metacyclic trypomastigotes obtained in vitro were infective to nude Balb/c hybrid mice. Zymodeme 1 parasites produced high parasitemias in this murine model; in contrast, zymodeme 2 parasites displayed lower parasitemias. Of a total of 27 T. cruzi isolates, 20 proved to be infective to mice, 12 gave enough parasites for further studies, and 8 of these were used for biological characterization. Results are compared with the infective clone Dm28 and Tulahuén strains maintained since 1954 in mice.

Animals↗
PubMed1990

Topical and systemic availability of 5-aminosalicylate: comparisons of three controlled release preparations in man.

The bioavailability of three pure 5-aminosalicylic (5-ASA) preparations (Asacol, Claversal, and Pentasa) was studied in 8 ileostomy patients and 12 normal subjects after 6 days of treatment with 2000 mg 5-ASA. The local bioavailability, reflected by the 5-ASA concentration was thereby measured at two clinically relevant areas of the gut: at the entrance to, and the exit from the colon. Estimates of the systemic bioavailability were obtained from the urinary excretions and the plasma values of 5-ASA and Acetyl-5-ASA (Ac-5-ASA) during the three regimens. The three preparations studied are designed to release 5-ASA at different levels in the intestine, but there was no significant difference in the 5-ASA concentrations in the ileostomy effluents (Asacol 1.8 mmol/L, Claversal 3.4 mmol/L, Pentasa 2.0 mmol/L, median values). However, we found a smaller urinary excretion of 5-ASA and Ac-5-ASA (5.2% vs Claversal 27.9% and Pentasa 23.0%, median values of ingested daily dose) and a lower concentration of Ac-5-ASA in the ileostomy effluents after Asacol treatment (0.8 mmol/L, median value) which indicates a more distal release from this preparation compared with Claversal (2.4 mmol/L, median value) and Pentasa (5.5 mmol/L, median value). In normal subjects a higher faecal water concentration of 5-ASA was found after Asacol (9.8 mmol/L, median value) compared with Claversal (5.0 mmol/L, median value), whereas no difference between the faecal water concentrations of Ac-5-ASA was found (Asacol 21.5 mmol/L, Claversal 21.6 mmol/L, median values). This can be explained by a larger systemic absorption of 5-ASA from Claversal, and accordingly Claversal treatment resulted in the largest urinary excretion of 5-ASA and Ac-5-ASA (43.7% vs Asacol 35.6% and Pentasa 31.6%, median values of ingested daily dose). The high Ac-5-ASA concentration in the ileostomy effluents and in the faeces after Pentasa, and the low plasma values, indicate a slow 5-ASA release from this preparation throughout the small and large intestine. The results of the study indicate that Asacol is released in the distal part of the small intestine, that Pentasa is gradually released in the small and large intestine, and that Claversal shows an intermediate release pattern.

Administration, Topical↗
PubMed1989

[Keratoacanthoma centrifugum of Miedzinski and Kozakiewicz].

We describe the case of one patient, 54-year-old male, with a keratoacanthoma centrifugum situated on the right auricular pavilion. The injury begins as a small nodule with a keratotic innermost part that rapidly is excavated, grows centrifugally, appearing as a new lesion, an expansion of the primary one, in the posterior higher region, with the same characteristics. These lesions join and perforate the auricular cartilaginous tissue.

Ear Cartilage↗